Reduction of steroid ketones with alkali metal borohydride



Patented Feb. 17, 1953 UNIT ST'H'E 2,628,966 REDUCTION OF STEROID KETONES WITH rem" oFFics ALKALI METAL BOROHYDRIDE Jersey No Drawing.

This invention is concerned generally with the selective reduction of ketone groupings to hy droxy radicals in steroid compounds containing other reducible linkages. More particularly, it relates to a novel process for selectively reducing 11 keto cyclopentanopolyhydrophenanthrene compounds containing at least one unsaturated carbon-nitrogen linkage to form the corresponding 11 hydroxy cyclopentanopolyhydrophenanthrene compounds without affecting the carbon-nitrogen linkage. This selective reduction procedure is especially valuable in the synthesis of ll-hydroxy-pregnene compounds such as the adrenal hormones, corticosterone and l7-hydroxy-corticosterone, which may be chemically represented as follows:

(EH20 R C Hz H O=0 =0 --o151 HO HO Oorticosteronc l7'hydroxy-corticosteronc The configuration of the ll-hydroxyl substituent in such naturally-occurring steroids, which has been found to correspond to that of the two angular methyl groups and the side chain of the steroid molecule, is conventionally designated ,8 and written above the plane of the ring system, i. e. a full line in the formulae. i Heretofore, the synthesis of cortical steroids I hydroxyiated at position 11 has encountered an i apparently insurmountable obstacle by virtue of the following chemical facts: (1) The poly- :functional character of this class of steroids and the fact that such cortical steroid-s ordiinarily possess additional keto substituents in the 3 and/or -positions; (2) the extremely low reactivity (ascribed to steric hinderance) of the ll-keto substituent; (3) the known susceptibility of the .c-hydroxyl group at position 11 to oxidation and elimination reactions, together with the seemingly anomalous inertness of the 11(5) hydroxyl to acylating agents.

Thus, when l1-ket010,13-cyclopentanopolyhydrophenanthrenes containing additional keto substituents (for example in the 3 and/or 20- positions) are reduced using conventional methods of hydrogenation or chemical reduction, it has been found that reduction of the keto Application November 25, 1950, Serial No. 197,648

18 Claims. (Cl. 260-3975) radicals in the 3 and 20-positions takes place preferentially to reduction of the ll-ketone. Only by employing relatively drastic reduction conditions, is it possible to reduce the ll-keto substituent and, under such drastic conditions of reduction, the 3 and 20-keto groups are likewise reduced. The compounds thus obtained, in attempted syntheses of cortical steroids, are 10,13 dimethyl cyclopentanopolyhydrophenanthrenes containing an 11([3)-hydroxy radical, and additional hydroxy radicals in the 3 and/or ZO-positions of the molecule. Attempts to preferentially oxidize the 3 and/or 20-hydroxy radicals to the corresponding keto substituents, while retaining the B-hydroxyl radical attached to the ll-carbon atom, have not been successful due to the comparatively high susceptibility'of the 11(5) -hydroxy grouping to oxidation. Anomalously, it has not been possible to protect the 11(5) -hydroxy group by acylation, while leaving the 3 and/or '20-hydroxy radicals free to be oxidized, since the 1l(,6)-hydroxyl group is subject to very pronounced steric hindrance and has resisted acylation by all methods tried. (See page 408 of the text Natural Products Related to Phenanthrene by Fieser and Fieser, 3rd edition, Rheinhold Publishing Corp., New York, 19%9.)

It was known previously that, when ll-keto- 10,13 dimethyl cyclopentanopolyhydrophenanthrene compounds containing additional keto groupings in the 3 and/or 2Q-positions were reacted with the usual ketonereagents, such as hydroxylamine, semicarbazide, arylhydrazines,

hydrogen cyanide, ethyl orthoformate, and the like, the ketone groupings in the 3 and/or ZO-positions reacted leaving the ll-keto radical unchanged. It was thus known heretofore how to prepare ll-keto-l0,1B-diamethylcyclopentano-l cyclopentanopolyhydrophenanthrenes are. key intermediates in the preparation of adrenal hormones containing a l'l-hydroxy sub stituent since they can be readily converted, by reaction with an oxidizing agent followed by a hydrolyzing agent, to the corresponding 1'!- hydroxy 20 keto 10,13 dimethyl cyclopentanopolyhydrophenanthrene compounds.

These 11 keto-10,13-cyclopentanopolyhydrophenanthrenes containing, in place of the ketone grouping in the 3 and/ or 20-positions, a grouping containing an unsaturated carbon-nitrogen linkage, were not previously considered to be of any use whatsoever as intermediates for the synthesis of 1l-hydroxy-l0,l3-dimethyl-cyclopentanopolyhydrophenanthrenes containing- 3 and/ or ZO-keto groupings. This was due to. the" fact that no method was known whereby the ll-keto group in such ll-keto 10,13 dimethyl-cyclopentanopolyhydrophenanthrene compounds could be reduced without, at the same time, reducing the unsaturated carbon-nitrogen linkages. For ex ample, ordinary methods of hydrogenation or chemical reduction drastic. enough to reduce the ll-keto-groupingsin such compounds, invariably also reduced the carbon-nitrogen linkages in the 3 and/or 20 substitutents. The object of the present invention, therefore, was to accomplish this selective reduction operation and thus make possible the preparation of cortical steroids hydroxylated at position 11.

' We have. now discovered that this selective reduction of the ll-keto substitutent in ll-keto- 10,13 dimethylcyclopentanopolyhydrophenanthrene compounds containing at least one, unsaturated carbon-nitrogen linkage can be achieved by reacting said ll-keto compound, in the presence of. a diluent, with an alkali metal borohydride, such as lithium borohydride, sodium borohydride, and the like. The alkali metal borohydrides, while being sufiiciently' reactive to. reduce the substantially unreactivc ll-keto substituent, do not have any appreciable reducing effect. on unsaturated carbon-nitrogen linkages present in the steroid molecule. This remarkable selective action (with respect to' unsaturated groupings in steroid compounds), shown by alkali metal borohydrides is indeed surprising in view of the fact that the closely related reducing agent, lithium aluminum hydride, does not possess this selective action. When an ll-keto-l0,13-dimethylcyclopentanopolyhydrophenanthrene containing an unsaturated carbon-nitrogen linkage is reacted with lithium aluminumhydride the carbonnitrogen linkage is reduced along with the 11- ketone grouping.

We employ as starting materials in our novel process ll-ket'o 1'0,l3'- cyclopentanopolyhydrophenanthrenes containing at least one unsaturated carbon-nitrogen linkage as for example, oximino, semicarbazido, or arylhydrazino-substituted ll-lceto 10,13 dimethyl-cyclopentanopolyhydrophenanthrenes such as 3-(oximino, semicarbazido, or arylhydrazino)-I1,20diketopregnane; 3,1bdiReto-ZO-i'oximino, semi'carbazido or arylhydrazinol-pregnane; 3-hydroxy-llketo-ZO-(oximino, semicarbazido or arylhydrazinc-)- -pregnane;, 3,2(1- Cdi'oximino, disemicarbazido or diarylhydrazino)-ll-keto-pregnane; 3-(oximine, semicarbazido or arylhydrazino)-ll,20- diketo-zl-hydroxy pregnane; 3,2l-dihydroXy-l1- keto-Zil-(oximino, semicarbazido or arylhydrazinol-pregnane; 3,1l-diketo-20a(oximino, semic-arbazido or arylhydrazino)-21-hydroxy-pregnanc; 3z-(oximino, semicarbazi'do or ar-ylhydrazino.) -1.1,20-diket.o 21 acyloxyapregnane; 3,11- diketo-ZO-(oximino, semicarbazido or arylhydrazino)-21-acyloxy-prcgnane; 3J20.--(dioximino, di-

semicarbazido or diarylhydrazino) 1 l -keto-2 1 -acyloxy-pregnane; 3-hydroxy-11-keto-20- (oximino, semicarbazido or arylhydrazino) 21 acyloxypregnane, A -3,20-(dioxlmino, disemicarbazido or diarylhydrazino) -11-keto-21-hydroxy pregnene, A -3,20-(dioximino, disemicarb-azido or. diarylhydrazino)-l1-keto-2l-acyloxy-prcgnene, and the like. Instead of protecting auxiliary keto radicals by conversion to the oximes, semicarbazones or arylhydrazones (the substitutents having unsaturated ca-rbon-nitrogen linkages in the illustrative examples set forth hereinabove), these keto radicals can be converted by reaction with hydrogen cyanide to the corresponding cyanhydrin such as 3,20-dihydroxy-ll-keto-20cyanopregnane; 3,20-dihydroxy-ll-keto-ZO-cyano-Zlaoyloxy pregnane; 3,20,2l-trihydroxy-ll-keto- 20-cyano pregn-ane; 3,2l-diacyloXy-1l-keto-ZO- hydroxy-ZO-cyano-pregnane; and the like.

We particularly prefer to employ, as starting materials in our procedure, 11-keto-10,l3-cyciopentanopolyhydrophenanthrene compounds containing a A" unsaturated linkage and a cyano radical attached to the (3-20 carbon atom such as A -l1-keto-20-cyano-pregnene; A -3,ll-dilreto-ZO-cyano-pregnene; A -3-hydroxy-l1-keto- ZO-cyano-pregnene; A -3,1l-diketo-ZO-cyano-21- hydroxy pregnene; A -3,21-dihydroXy-ll-keto- ZO-cyano-pregnene; A 3 hydroxy-ll-keto-20- cyano-Zl-acyloxy pregnene, A -3,ll-diketo-29- cyano-21-acetoxy' pregnene; A. -3,11-diketo-20- cyano-2l-acyloxy-pregnenes, as well as A -llketo-20-cyano-l0, l3-dimethyl-cyclopentanopolyhydrophenanthrene compounds containing additional unsaturated carbon nitrogen linkages such as A -3-(oximino, semicarbazido or arylhydrazino)-ll-keto-ZG-cyano-pregnene; A -3-(oximino, semicarb'azido or arylhydrazino) -11-keto-20- cyano 21 hydroxy pregnene; A -3- (oximino, semicarbazido 0r arylhydrazino)-1l-keto-20cyano-Zl-acyloXy-pregnene, and the like.

It will. be noted that the starting materials described in the preceding paragraph include A"- ll-keto-ZO-cyano-pregnene compounds in which a keto grouping in the 3-position has been pro tected by conversion to an oximino, semicarbazido 01' aryl-hydrazino grouping. It is an important embodiment of our invention that A"- 1l-keto-20-cyano-pregnenes containing a S-ketosubstituent can be protected by forming the corresponding ketal, that is the A -3,3-dialkoxy-1lketo-Zil-cyano-pregnene compound, such as A"- 3,3-dimethoxy-11-keto-2Q-cyano-pregnene; A 3,3-diethoxy-1l-keto-2Q-cyano-2l-hydroxy-pregnene; A -3,3-diethoxy 11 keto 20 cyano-2lacyloxy-pregnene, and the like. These compounds, which contain an unsaturated carbonnitrogen linkage (the ZO-cyano group) and a ketal group can also be utilized as starting materials in carrying out our invention.

In carrying out our novel process, the llkQtC' 10,13 dimethyl cyclopentanopolyhydrophenanthrene compound containing at least one unsaturated carbon-nitrogen linkage, is reacted with an alkali metal borohydride, such as lithium borohydride, sodium borohydride, and the like. The reaction is ordinarily conducted in the presence of a diluent, preferably in the presence of a solvent such as tetrahydrofuran, dimethyl formamide, diethyl ether, and the like. It is ordinarily preferred to carry out the reaction by aciding a tetrahydrofuran solution of the ll-keto-- 10,13 dimethyl cyclopentanopolyhydrophenanthrene compound containing at least one unsaturated carbon-nitrogen linkage to a tetrahydrofuran solution of the alkali metal borohydride reducing agent. This addition of the ll-ketosteroid compound to the reducing agent is preferably conducted portionwise, while maintaining the temperature of the reaction mixture at approximately 25 C. However, with the more active alkali metal borohydride (lithium borohydride), the reaction can be carried out at a lower temperature with lengthening of the reaction time. Conversely, with the less active sodium borohydride, a higher temperature may be necessary, it ordinarily being preferred to conduct the reaction, when using sodium borohydride as the reducing agent, at temperatures of about 60-70 C.

Although the preferred solvent for carrying out the reaction is tetrahydrofuran, it is sometimes preferred to utilize dimethylformamide as the solvent, in view of the fact that this liquid is an excellent solvent for many steroid compounds which are difficultly soluble in other solvents. In this connection, it should be pointed out that dimethylformamide is ordinarily reduced by active reducing agents; the fact that it is not affected by alkali metal borohydrides makes possible its employment as a solvent in this reduction operation.

Although it is ordinarily preferred to maintain the reaction temperature at about 25 C., somewhat lower temperatures down to 0 C. when using lithium borohydride, as well as higher temperatures up to 70 C., when using sodium borohydride, can be employed. When the reaction is carried out with lithium borohydride at thepreferred temperature of about 25 C., the reaction is ordinarily substantially complete in less than approximately one hour. When the reaction is carried out with sodium borohydride at the preferred temperature of about 65 C., the reaction is substantially complete in less than 24 hours.

After completion of the reaction, the resulting 11(B-hydroxy-l0,13 dimethyl cyclopentanopolyhydrophenanthrene compound (in which the unsaturated carbon-nitrcgen linkages are identical with those present in the starting material) is recovered from the reaction mixture by conventional means. This is ordinarily accomplished by cautiously acidifying the reaction mixture, preferably utilizing aqueous acetic acid, thereby decomposing excess alkali metal borohydride. The 11(,8) -hydr0xy substituted steroid compounds can then be recovered by evaporating the reaction mixture to a small volume, preferably in vacuo and diluting the concentrate with water. The product which separates, frequently in the form of, an oil, can then be extracted from this aqueous mixture utilizing conventional water-immiscible solvents such as benzene, ether, chloroform, ethyl acetate, and the like. The extract of ll(/$)hy droxy-steroid is then purified by conventional means, as for example, bye-lashing successively with water and dilute queens alkaline solution, followed by drying. The product is recovered from the extract by evaporating the solvent therefrom, and can be further purified by recrystallization from solvents such as aqueous acetone, benzene, and the like. Where recrystallization from an organic solvent alone is insufficient to accomplish purification, it has been found convenient to subject the extract to a preliminary chromatographic fractionation utilizing activated alumina as the adsorbent.

Thefollowing examples illustrate methods of carrying out the present invention, but it is to Example 1 A mixture of 35.5 g. of A "-3.11dike ydroXy-ZO-cyano-pregnene, 22.2 g. of ethyl orthoformate, 0.69 g. of absolute ethyl alcohol, 200 ml. of sodium-dried benzene and 10 drops of concentrated sulfuric acid was heated with occasional agitation at a temperature of '70-'75 C. for a period of approximately 2 hours. The resulting light-brown benzene reaction solution was cooled to room temperature and 5 g. of solid sodium bicarbonate was added followed by 150 ml. of a 5% aqueous solution of sodium bicarbonate. The mixture was shaken vigorously, and theaqueous layer was separated from the benzene solution. The aqueous layer was then extracted with two ml. portions of ether, and the ether extracts were combined with the benzene solution. The combined benzene-ether solution was washed with two ml. portions of water, and one 100 ml. portion of saturated aqueous sodium chloride solution and then dried over 10 g. of anhydrous magnesium sulfate. The solvents were then evaporated in vacuo from the dry benzene-ether solution to give 45.5 g. of A"-3,3diethoxy-ll-keto 20 cyano-Zl-hydroxy-pregnene, which was obtained in the form of a fiufiy, paleyellow, amorphous solid; the infra-red absorption spectrum (chloroform solution) showed the principal bands at 2.85 m (--OH)', 4.57 m (--CEN), 5.83 nm C=O), 6.08 m C=C and 45 g. of A -3,3-diethoxy-l1-keto-20-cyano-21- hydroxy-pregnene, obtained as described hereinabove, was dissolved in 300 ml. of dry tetrahydrofuran (dried over metallic sodium) and this solution was added, dropwise, with agitation over a /2 hour period, to a solution of 9.7 g. of lithium borohydride in 300 ml. of dry tetrahydrofuran, while maintaining the temperature of the mixture at approximately 25 (3. The resulting mixture was stirred for an additional period of 20 minutes at a temperature of 25 C., and was then cooled and stirred for 10 minutes at about 5 C. 600 ml. of aqueous acetic acid containing ml. of glacial acetic acid was added cautiously, with stirring, to the resulting mixture whereupon a vigorous evolution of gas occurred. The resulting mixture was evaporated in vacuo to a volume of approximately 600 ml., and the concentrated solution was then diluted with approximately 600 ml. ofwater. The oily organic layer which separated was then extracted "from the mixture utilizing 600 ml. of a 5:1 benzene-ether mixture followed by two 200 ml. portions of benzene. The combined benzene-ether extracts were washed with two 200 ml. portions of water, one 209 portion of 5% aqueousj' sodium bicarbonate solution, and one 200 nil; portion of saturated aqueous sodium chloride solution. The washed benzene-ether extract was then dried over 30 g. of anhydrous magnesium sulfate, the dry solution wasfiltered, and the solvents were evaporated therefrom in vacuo to give 40.1 g. of crude A -3,3-diethoxy-11,21-dihydroxy-20-cyano-pregnene which was obtained in the form of a fiuffy, pale-yellow, amorphous solid. 7

401 g. ofcrude A '3,3-"dieth0{y 11,21 dlhydrOXy-ZO-cyano-pregnene, prepared as described hereinabove, was dissolved in a mixture of 425 ml. of acetone and 55 ml. of water. To this solution was added 4.0 ml. of 2.5 N aqueous hydrochloric acid, and the resulting solution was allowed to stand at room temperature for a period of about 30 hours. '25 ml. of aqueous sodium bicarbonate solution was then added to the reaction mixture, and the resulting solution was evaporated in vacuo to a small volume, thereby evaporating substantially all of the acetone present in the solution; during this evaporation, a pale-yellow oil separated. The residual material was diluted with 800 ml. of water, and the oily organic material was extracted from the aqueous mixture utilizing one 400 ml. portion and two 300 ml. portions of chloroform. The combined chloroform extracts were washed successively with one 300 ml. portion of 5% aqueous sodium bicarbonate solution, one 300 ml. portion of water, and the washed chloroform extracts were then dried over 15 g. of anhydrous magnesium sulfate. The dry chloroform solution was filtered and the chloroform evaporated in vacuo to give 38.8 g. of crude A -3-keto-11,21-dihydroxy-20-cyano-pregnene which was obtained in the form of a pale, buff-colored, partly crystalline solid. This crude material, after one recrystallization from aqueous acetone, gave 15.3 g. of substantially pure A "-3-keto-11,21-dihydroxy-20 cyano pregnene which was obtained in the form of colorless needles; M. P. 216.5-218.5 C. (melted partly at 206 C. then resolidified). An analytically pure sample obtained by several recrystallizations from aqueous acetone melted at 217.5-221.5 C. (melted partly at 207-210 C.', then solidified); [a1]: 24.4 (1.03 in acetone);

Found: C, 74.12; H, 8.73.

7 Example 2 Twenty grams of A -3,11-diketo-20-cyano-21 hydroxy-pregnene was dissolved in 300 ml. of glacial acetic acid and to this solution was added a solution containing 12.55 g. of semicarbazide hydrochloride and 12.55 g. of anhydrous sodium acetate dissolved in 28 ml. of water and 28 ml. of glacial acetic acid; the latter solution was rinsed into the reaction mixture with an additional 44 ml.'of glacial acetic acid. The resulting mixture was heated to a temperature of 55-70 Cffor a period of approximately 2 hours during which time a small amount of crystalline material separated. The resulting suspension was evaporated in vacuo to a thick slurry of crystalline solid, and 200 ml. of water was added to said slurry. The resulting aqueous mixture was agitated vigorously to suspend caked material, the slurry was then filtered and the crystalline product washed twice with water to give 24.2 g. of colorless needles which melted at 225-230 C. with evolution of gas. One recrystallization of this product from'methanolchloroform aflforded 20.2 g. of substantially pure A -3 semicarbazido-ll-keto-ZO-cyano-Zlhydroxy-pregnene; M. P. 238-240 C. (vigorous evolution of gas) This product was further purified by repeated recrystallization from methanolchloroform and the product dried at 140 C. to

give analytically pure A"-3-semicarbazido-1l'-' keto 20 cyano 21 hydroxy-pregnene; M. P. 244-245 C. (evolution of gas). for C23H32O3N4: N, 13.58. Found: N, 13.47;

Analysis calcd Example 3 12.36 g. of A -3-semicarbazido 11 keto 20 cyano-21-hydroxy-pregnene (M. P. 238-240 C.) was dissolved in 1500 ml. of dry tetrahydrofuran (dried over metallic sodium), and this solution was added with stirring, over a period of approximately hour, to a solution of 4.36 g. of lithium borohydride in 200 ml. of dry tetrahydrofuran, while maintaining the temperature of the mixture at approximately 25 C. The resulting mixture was stirred for an additional period of 20 minutes at a temperature of 25 C., and was then cooled and stirred for 10 minutes at about 5 C. 450 ml. of aqueous acetic acid containing 51.5 ml. of glacial acetic acid was then added cautiously, with stirring, to the resulting mixture, and the clear, colorless reaction mixture was evaporated in vacuo under a nitrogen atmosphere to a volume of approximately 400 ml. The colorless oily organic material which separated was extracted from the mixture utilizing one 350 ml. portion of chloroform and two 150 m1. portions of chloroform. The combined chloroform extracts were washed with two 250 ml. portions of water and with one 200 ml. portion of 5% aqueous sodium bicarbonate solution, and the washed chloroform extracts were dried over 10 g. of anhydrous sodium sulfate. The dry chloroform solution was then filtered and the chloroform evaporated to give 11.5 g. of crude A -B-semicarbaZido-I1,21- dihydroxy 20 cyano-pregnene which was obtained in the form of a gummy, buff-colored solid.

4.5 g. of this material was mixed with 15 ml. of glacial acetic acid, 7.5 ml. of water, 9.05 g. of anhydrous sodium acetate and 9.0 ml. of 90% py uvic acid, and the mixture was heated at a temperature of C. in an atmosphere of nitrogen for a period of about 3 hours. The reaction mixture was cooled to room temperature, an additional 0.9 ml. of pyruvic acid was added thereto, and the resulting mixture was heated under nitrogen at a temperature of 80 C. for an additional one-hour period. The resulting mixture was allowed to stand overnight at room temperature whereupon a considerable quantity of crystalline material separated. ml. of water was added to this mixture, and the organic material was extracted therefrom utilizing one 80 ml. portion and three 35 ml. portions of chloroform. The combined chloroform extracts were washed with two 50 ml. portions of water, two 50 ml. portions of 5% aqueous sodium bicarbonate solution, again with 50 m1. of water, and the washed chloroform solution was then dried over 5 g. of anhydrous magnesium sulfate. The dry chloroform solution was then filtered and the solvent was evaporated from the filtrate in vacuo to give 4.25 g. of partly crystalline, light, buff-colored material. This product, after one recrystallization from acetone, afforded 1.75 g. of substantially pure A -3-keto-11,21-dihydroxy-2O-cyanopregnene; which was obtained in the form of colorless needles; M. P. 2165-2195 C. (melted partly at 206.5" C. to 208 C. then resolidified); there was no depression in melting point when this material was admixed with A -3-keto-ll,2ldihydroxy-20-cyano-pregnene as prepared via the 3-diethyl ketal as described in Example 1 hereinabove.

Example 4 1.07 g. of A -3,1l-diketo-Z1-hydroxy-20-cyano-pregnene was dissolved in '23 ml. of dry tetrahydrofuran (dried over metallic sodium) and this solution was added, dropwise, with stirring, over a 10 minute period, to an ice-cold solution of 0.15 g. of lithium borohydride in 6 m1. of dry tetrahydrofuran. The solution of the diketone was rinsed into thesolution containing lithium borohydride by means of an additional 2 ml. of dry tetrahydrofuran, and the resulting mixture was then stirred for an additional period of 20 minutes while maintaining the temperature at approximately C. 20 ml. of water was then added dropwise to the cold reaction mixture, followed by the oautious addition of 2 ml. of glacial acetic acid. The resulting mixture was then stirred for a period of about 10 minutes, and the clear colorless reaction mixture was evaporated in vacuo to a volume of about 25 ml., whereupon a colorless oil separated. 25 ml. of ether was added to the oily mixture, and the resulting mixture was allowed to stand overnight whereupon a crystalline material separated from the mixture. The crystalline product was recovered from the water-ether mixture by filtration to give 0.5 g. of rosettes of colorless prisms which were further purified by a single recrystallization from acetone to give substantially pure A -3,21-dihydroxy-11-l :eto-20-cyano-pregnene; M. P. 251- 2575 C. (with slight previous softening); no depression in melting point was observed when this material was admixed with authentic A 3,21 dihydroxy 11 keto 20 cyano pregnene; comparative infrared spectra of this material and of the authentic specimen confirm its identity.

Example 5 5.35 g. of A -3,2l-dihydroxy-11-keto-20-cyano-pregnene was dissolved in 100 ml. of dry tetrahydrofuran (dried over metallic sodium) and this solution was added, dropwise, with stirring, over a 30 minute period, to a solution of 1.45 g. of lithium borohydride in 75 ml. of dried tetrahydrofuran, while maintaining thetemperature of the mixture at 25 C.; the solution of the pregnene compound was rinsed into the solution of lithium borohydride by means of an additional 25 ml. of tetrahydrofuran. The resulting mixture was stirred for an additional period of 30 minutes at a temperature of 25 C., and 100 ml. of aqueous acetic acid solution was added cautiously, with stirring, to the mixture thereby decomposing the excess lithium borohydride. The resulting clear, colorless solution was evaporated in vacuo to a volume of approximately 100 ml., and the colorless oil which separated was extracted from the mixture utilizing three 50 ml. portions of ethyl acetate. The ethyl acetate extracts were combined and washed successively with one 30 ml. portion of water, and with one 30 ml. portion of a saturated solution of sodium chloride. 7 The washed ethyl acetate solution was then dried over 5 g. of anhydrous magnesium sulfate, the dry solution was filtered, and the solvent evaporated from the filtered solution in vacuo to give a colorless amorphous solid. This material was crystallized from acetone-benzene to give 5.80 g. of substantially pure A -3,11(,B),21- trihydroxy 20 cyano pregnene which was obweight loss for ZCcI-Ic, 30.29. Found: weight loss on drying at 140 0., 29.98. Thus after drying at 140 C. there was obtained substantially pure, benzenefree A" 3,11,( 8) ,21 trihydroxy 20- cyano-pregnene. Calcd for C22H3303N: C, 73.50; H, 9.25; N, 3.90. Found: (dried at 140 C.) C, 74.11; H, 9.11; N, 3.91.

Example 6 0.5 g. of A I-3,11,20-triketo-17,2l-dihydroxypregnene, 0.483 g. of hydroxylamine hydrochloride and 0.57 g. of anhydrous sodium acetate were dissolved in 35 ml. of absolute ethyl alcohol and the resulting solution was heated at a temperature of 70 C. for a period of 3 hours. The resulting solution was evaporated in vacuo to a volume of approximately 10 ml., and 30 ml. of water was added to the concentrate thus obtained. The buff-colored oil which separated became crystalline upon trituration. The crystalline product was recovered by filtration, washed thoroughly with water, and dried to give 0.495 g. of crude A 3,20 dioximino 11 keto 17,21 dihydroxy-pregnene; M. P. 184-187 C. dec. This product was further purified by repeated recrystallizations from methanol to give substantially pure A -3,20-dioximino-11-keto-1'7,21-dihydroxypregnene which was obtained in the form of colorless needles; M. P. 199-200 C. [a]D=+166 (1.0 inacetic acid) iggfi 24.00 3., Ef 534 Analysis calcd. for C21H30O5N22 C, 64.59; H, 7.74; N, 7.18. Found: C, 64.37; H, 7.83; N, 6.97.

Example 7 1.0 g. of A -3,20-dioximino-11-keto-1'7,2l-dihydroxy-pregnene was dissolved in 15 ml. of dry tetrahydrofuran dried over metallic sodium) and this solution was added, with stirring, over a 7 period of approximately hour, to a solution of tained in the form of colorless, heavy needles 0.4 g. of lithium borohydride in 20 ml. of dry tetrahydrofuran, while maintaining the temperature of the mixture at approximately 25 C. The resulting mixture was stirred for an additional period of 40 minutes at a temperature of 25 'C., and was then cooled to 5 C. 50 ml. of 10% aqueous acetic acid was added cautiously, with stirring, to the cold reaction mixture, and the resulting mixture was stirred for an additional 10 minutes. The clear colorless solution thus obtained was evaporated in vacuo to a small volume, and 30 ml. of water was added to the concentrated solution. The colorless solid which separated from the aqueous mixture was then I recovered by filtration, washed thoroughly with water, and dried to give 0.93 g. of crude A -3,20- dioximino 11,17,21 trihydroxy pregnene; this material did not melt at 310 C.

The crude product thus prepared was purified by precipitation from a saturated solution in methanol by the addition of water to give substantially pure A -3,2-0-dioximino-l1,17,21-trihy- I droxy-pregnene, which was obtained in the form of a colorless powder which did not melt at 310 C.; [a] (1.0 in acetic acid);

Infrared absorption spectrum showed that the carbonyl bond was completely absent. Analysis Calcd for C21H32O5N2: (164.26; H, 8.22; N, 7.14. Found: C, 63.96; H, 7.59; N,6.90.'

Example 8 1.78 g. of A -3, ll-diketo-ZO-cyano-Zl-hydroxypregnene' was dissolved in 25 ml. of tetrahydrofura'n containing 0.4 ml. of 2.5'N' aqueous sodium hydroxide, and to this solution was added, all at once, a solution of 0.84 g. of sodium borohydride in 5.0 ml. of tetrahydrofuran, 5.0 ml. of water and 0.4 ml. of 2.5 N aqueous sodium hydroxide. The mixture was heated under reflux for a period of approximately twenty-four hours. The reaction mixture was then cooled to room temperature, and 35 ml. of 10% aqueous acetic acid was added to the cooled mixture thereby decomposing excess sodium borohydride.

"The resulting clear, colorless solution was evaporated'in vacuo to a small volume thereby substantially removing the tetrahydrofuran. The suspension of colorless oil thus obtained was diluted with 100 ml. of water and the oil was extracted from the aqueous mixture with three 50 1. portions of ethyl acetate. The combined ethyl acetate extracts were washed successivelywith two 50 ml. portions of water, with two 50 ml. portions of aqueous sodium bicarbonate solution, and with one 50 ml. portion of saturated aqueous sodium chloride solution. The washed ethyl acetate solution was dried over 5 e. of anhydrous magnesium sulfate, the solution was filtered and the solvent was evaporated therefrom in vacuo to give 1.92 g. of a colorless amorphous solid. This materialwas crystallized from acetone-benzene to'give 1.71 g. of substantially pure A -3,11%),2l-trihydroxy-ZO-cyanopregnene'which was obtained in the form of colorless needles containing two molecules of benzene of crystallization; M. P. 99.5-105 C. (vigorous evolution of gas).' The sample exhi ted igg e 2230 It, mm 268 and the infrared absorption spectrum showed the complete absence of the carbonyl absorption band, as wellas. identity of this material with A 7, 3,1l([i) .21 trihydroxy 20 cyanoprege nene prepared bythe lithium borohydride reduce tion of: .A 3,21-,dihydrox-y:lleketo.-, 20 cyanopregnene as described in Example 5 hereinabove.

Example 9 2.32. grams of A -3,3-dietho xy 11 keto-ZO- wand-21-hydroxy-pregnene was dissolved in 20 ml: of tetrahy'drofuran, and to this solution was added a solution of 0.84 g. of sodium borohydride in" inl. of 'te'tr aliydrofuran, 10 ml. of water and 0.2 ml. of 2.5 Nadueous sodium hydroxide. The mixturewas heated. under reflux for a period of approximately hours. The reaction mixture was then 'cooled toroom temperature, and ml. of 10% aqueous acetic acid was added to the cooled mixture. thereby decomposing excess sodium borohydride.

The resulting clear, colorless solution was evaporated in vacuo to a volume of about 40-50 ml., and the pale-yellow oil which separated was extracted with three m1. portions of ethyl acetate. The ethyl acetate extracts were combined and the. resulting ethyl acetate solution was washed successively with two 50 ml. portions of water, with two 50 ml. portions of 5% aqueous sodium bicarbonate solution, with one 50' ml. portion of water, and with one 50 ml. portion of saturated" aqueous sodium chloride solotion. The washed ethyl acetate solution was dried over5 g. of anhydrous magnesium sulfate, the solution was filtered, and the solvent was evaporated therefrom in vacuo to give 1.985 g. of 11 3,3 diethoxy 11 fl y r y cyano-pregnene which was obtained in the form of a pale bull-colored amorphous solid.

This material was dissolved in 25 ml. of acetone, and to this solution was added 5 ml. of water and 0.2 ml. of 2.5 N aqueous hydrochloric acid. This solution was allowed to stand at room temperature for a period of approximately 20 hours, 5.0 ml. of 5% aqueous sodium bicarbonate solution and 20 ml. of Water were added thereto, and the resulting solution was evaporated in vacuo to a small volume, thereby removing the major portion of the acetone. The buff-colored oil which separated was extracted with one 50 m1. portion and two 30 ml. portions of ethyl acetate. The ethyl acetate extracts were combined and the ethyl acetate solution was washed successively with two 40 ml. port-ions of water, with one 40 ml. portion of 5% aqueous sodium bicarbonate solution, with one 40 m1. portion of water, and with one 40 ml. portion of saturated aqueous sodium chloride solution. The washed ethyl acetate solution was dried over 5 g. of anhydrous magnesium sulfate, the solution was filtered, and the ethyl acetate was evaporated therefrom in vacuo to give a partly crystalline pale, bull-colored residue weighing 1.705 g. This material was recrystallized from acetone to give 0.7-3 of substantially pure A -3-keto-11( 8),21- dihydroxy-ZO-cyanQ-pregnene Which was obtained in the form of rosettes of heavy colorless needles; M. P. 215-218" C. with softening at 213 C. (partly melted at 203-206 C., then resolidified) no depression in melting point was observed when this material was mixed with A 3 keto 11( 3).,21 dihydroxy 20 cyanopregnene prepared as described in Example 1.

Various changes and modifications may be made in carrying out the present invention without departing from the spirit and scope thereof. Insofar as these changes and modifications are within the purview of the annexed claims, they are to be considered aspart of the present invention.

.ing at least one unsaturated carbon to nitrogen linkage, without substantially affecting said carbon to nitrogen linkage, which comprises reacting said keto-substituted steroid compound with lithium borohydride thereby forming the corresponding hydroxy-substituted steroid compound.

3. The process ofreducing a ketone grouping in a keto-substituted steroid compound contain ing at least one. unsaturated carbon to nitrogen linkage, without substantially aifecting said carbon to nitrogen linkage, which comprises reacting said keto-substituted steroid compound with. sodium borohydride thereby forming the corresponding hydroxy-substituted steroid compound.

, 4. The process of reducing the ll-keto-substituent in an l1-keto-10,13-dimethyl-cyclopentanopolyhydrophenanthrene compound containing at least one unsaturated carbon to nitrogen linkage, without substantially afiecting said carbon to nitrogen linkage, which comprises bringing said 1l-keto-10,13-dimethyl-cyclopentanopolyhydrophenanthrene compound into intimate contact with an alkali metal borohydride thereby forming the corresponding ll-hydroxy- 10,13 dimethyl cyclopentanopolyhydrophenanthrene compound.

5. The process of reducing the ll-keto substituent in an 11-keto-10,13-dimethyl-cyclopentanopolyhydrophenanthrene compound containing at least one unsaturated carbon to nitrogen linkage, without substantially affecting said carbon to nitrogen linkage, which comprises bringing said 1l-keto-l0,13-dimethyl-cyclopentanopolyhydrophenanthrene compound into intimate contact with lithium borohydride thereby forming the corresponding ll-hydroxy-10,13-dimethyl cyclopentanopolyhydrophenanthrene compound.

6. The process of reducing the ll-keto substituent in an 11-keto-10,13-dimethyl-cyclopentanopolyhydrophenanthrene compound containing at least one unsaturated carbon to nitrogen linkage, without substantially aiiecting said carbon to nitrogen linkage, which comprises bringing said 11 keto 10,13 dimethyl cyclopentanopolyhydrophenanthrene compound into intimate contact with sodium borohydride thereby forming the corresponding 11-hydroxy-10,13- dimethyl cyclopentanopolyhydrophenanthrene compound.

7. The process of converting an 11-keto-10,13- dimethyl cyclopentanopolyhydrophenanthrene compound containing at least one unsaturated carbon-nitrogen linkage to the corresponding 11(6) hydroxy 10,13 dimethyl cyclopene tanopolyhydrophenanthrene compound without substantially affecting the carbon-nitrogen linkage, which comprises reacting said 11-keto-10,13- dimethyl cyclopentanopolyhydrophenanthrene compound with an alkali metal borohydride, said reaction being carried out by bringing the reactants together in solution in an organic solvent at a temperature within the range of to 70 C.

8. The process which comprises reacting an alkali metal borohydride with an ll-keto-pregnene compound having attached to the carbon atom in the 20-position of the molecule a substituent containing an unsaturated carbon to nitrogen linkage, thereby converting the ll-keto substituent to an 11(5) -hydroxy radical without substantially afiecting the carbon to nitrogen linkage in the substituent attached to the 20- carbon atom.

9. The process of preparing A -3-semicarbaZid0-11(]8),21 dihydroxy 20 cyano pregnene which comprises reacting A -3-semicarbazido-ll keto 20 cyano 21 hydroxy pregnene with lithium borohydride, said reaction being carried out by bringing the reactants together in solution in tetrahydrofuran at a temperature of approximately 25 C.

10. The process of preparing A "-3,3-diethoxy- 11(;3),21 dihydroxy 20 cyano pregnene which comprises reacting A -3,3-diethoxy-11- keto-20-cyano-2l-hydroxy-pregnene with lithium borohydride, said reaction being carried out '14 tetrahydrofuran at a temperature of approxi-- mately 25 C.

11. The process of preparing A "-3,11(p),21- trihydroXy-20-cyano-pregnene which comprises reacting A" 3,21-dihydroxy 11 keto 20- cyano-pregnene with lithium borohydride, said reaction being carried out by bringing the reactants together in solution in tetrahydrofuran at a temperature of approximately 25 C.

12. The process of preparing A -3,20-disemicarbazido 11(5) ,17,21 trihydroxy pregnene, which comprises reacting A -3,20-disemicarbazido-11-keto-17,21-dihydroxy-pregnene with sodium borohydride, said reaction being carried out by bringing the reactants together in solution in tetrahydrofuran at a temperature of approximately 60-70 C.

13. The process of preparing A17-3,11(B) ,21- trihydroxy-20-cyano-pregnene which comprises reacting A -3,11-diketo-20-cyano-21-hydroxypregnene with sodium borohydride, said reaction being carried out by heating a solution of the reactants in tetrahydrofuran under reflux.

14. The process of converting a A -11keto- 20-cyano-pregnene compound to the corresponding A -11(6)-hydroxy-20-cyano-pregnene compound without substantially afiecting the carbon to nitrogen linkages in the 20-cyano radical, which comprises reacting said A "-11-keto-20- cyano-pregnene compound with an alkali metal borohydride.

15. The process of converting a n -ll-ketozll-cyano-pregnene compound to the corresponding A -11(3) -hydroxy-ZO-cyano-pregnene compound without substantially affecting the carbon to nitrogen linkages in the 20-cyano radical, which comprises reacting said A -11-keto-20- cyano-pregnene compound with lithium borohydride.

16. The process of converting a A -11-keto- ZO-cyano-pregnene compound to the corresponding A -1108) -hydroxy-20-cyano-pregnene compound without substantially affecting the carbon to nitrogen linkages in the 20-cyano radical, which comprises reacting said A -l1-keto-20- cyano-pregnene compound with sodium borohydride.

17. The process which comprises reacting an alkali metal borohydride with a A -11-keto-17- hydroxy-pregnene compound having substituted imino groupings attached to the 3- and 20-carbon atoms, and having a 21-position substituent selected from the group which consists of hydroxy and acyloxy radicals, thereby converting the ll-keto radical to an l1(B)-hydroxy grouping without affecting the other substituents present in the molecule.

18. The process which comprises reacting lithium borohydride with a A -ll-keto-17-hydroxypregnene compound of the formula:

CHzOR wherein R is a radical selected from the class which consists of hydrogen and acyl radicals, and Q is a radical selected from the class which conby bringing the a tants tose h rin sol t in sists of oximino, ,semicarbazido and aryl-hydra- 15 16 zinc: radicals, to: produce a. compound of the wherein R and Q have the significance above formula defined. onion ROBERT P. GRABER.

C= Q NORMAN L. WENDLER.

,' 5 -r-on REFERENCES CITED The following references are of record in the file of this patent: 

1. THE PROCESS OF REDUCING A KETONE GROUPING IN A KETO-SUBSTITUTED STEROID COMPOUND CONTAINING AT LEAST ONE UNSATURATED CARBON TO NITROGEN LINKAGE, WITHOUT SUBSTANTIALLY EFFECTING SAID CARBOND TO NITROGEN LINKAGE, WHICH COMPRISES REACTING SAID KETO-SUBSTITUTED STEROID COMPOUND WITH AN ALKALI METAL BOROHYDRIDE THEREBY FORMING THE CORESPONDING HYDROXY-SUBSTITUTED STEROID COMPOUND. 